Hydrothermal Synthesis of Nanorods and Nanowires of Mg/Al Layered Double Hydroxides

Layered double hydroxides (LDHs) are a class of synthetic anion clays, characterized by the formula[MⅡ1-xMⅢx (OH)2]x (An- )x/n·yH2O (where M =metal and A = anion, usually carbonate)[1-3]. A large number of LDHs with a wide variety of M Ⅱ-M Ⅲ cation pairs including M Ⅰ-M Ⅲ ( e. g. , Li-Al ) and M Ⅱ-MⅣ( e. g. , Co-Ti) have been reported. Thus the identities of the cations(MⅠ , MⅡ , MⅢ and MⅣ) and the interlayer anion (An-) together with the value of the stoichiometric coefficient (x) may vary widely, giving rise to a large class of isostructural materials.     

简化形式的积分中值定理另一种表述

阐述了简化形式的积分中值定理中f(x)不要求连续的情况下成立的条件.即"设函数f(x)在闭区间[a,b]上可积,同时f(x)在[a,b]上有原函数,则存在ξ∈(a,b),使∫ from x=a to b f(x)dx=f(ξ)(b-a)成立",并且给出了简洁的证明.     

Determination and Temperature Dependence of Plateau Modulus for Polymerization of Propylene to Isotactic Polypropylene with Ultra-high Molecular Weight under Catalysis of Ziegler-Natta Catalyst

The viscoelastic behavior of isotactic polypropylene with ultra-high molecular weight (UHPPH) and broad molecular weight distribution(MWD), produced in the presence of Ziegler-Natta catalyst, was investigated by means of oscillatory rheometry at 180 and 200 ℃, whose loss modulus(G") plots at 180 and 200 ℃versus the natural logarithm of angular frequency(ω) present a pronounced maximum at 34.35 and 69.21 rad/s, respectively, and do not show a maximum peak at 0. 01-100 rad/s for Ziegler-Natta catalyzing ethylenepropylene random copolymerization (PPR) with a conventional molecular weight and broad MWD. The fact indicates that the high molecular weight is responsible for a maximum peak of G"(ω) vs. lnω curves for UHPPH. This makes it possible to determine the plateau modulus (G0N) of UHPPH from a certain experimental temperature G"(ω) curve directly. For UHPPH, the G0N determined to be 4. 28×105 and 3. 62×105 Pa at 180and 200 ℃, respectively, decreases with the increase of temperature and is independent of the molecular weight, which directly confirms reputation theoretical prediction that the G0N has no relation to the molecular weight.     

Simultaneous Determination of Seven Active Compounds in Radix Salviae Miltiorrhizae by Temperature-Controlled Ultrasound-Assisted Extraction and HPLC

A simple and effective high-performance liquid chromatographic (HPLC) method has been developed for simultaneous quantification of three phenolic acids (3,4-dihydroxyphenyllactic acid (Chinese name danshensu), protocatechuic aldehyde, and salvianolic acid B) and four diterpenes (dihydrotanshinone I, cryptotanshinone, tanshinone I, and tanshinone II_A) in radix salviae miltiorrhizae. Chromatography was performed on a 250 mm × 4.6 mm i.d., 5-μm particle size, C₁₈ column. The mobile phase was a linear gradient prepared from 0.1% (v/v) aqueous formic acid and acetonitrile at a flow-rate of 1.0 mL min⁻¹. All the target components were well separated with high resolution and without interference. Good linearity (R ² > 0.999) was observed over the concentration ranges investigated, and intra-day and inter-day precision were high. Temperature-controlled ultrasound-assisted extraction was used to prevent hydrolysis of thermally unstable components during the sample-extraction procedure, and the extraction conditions were carefully optimized. Recovery of the seven components was from 98.45 to 100.63% and relative standard deviations were always <1.5%. The validated method was successfully used for simultaneous quantification of the three phenolic acids and the four diterpenes in radix salviae miltiorrhizae of different geographic origins.     

利用预失真条纹校正PMP系统投影仪畸变的研究*

依据摄像机畸变模型提出了一种投影条纹相位畸变校正方法来简化相位-高度映射关系.该方法首先通过投两套互相垂直的相移正弦条纹,以相位值代替投影仪像素坐标,将投影仪当成摄像机看待,标定出投影仪的内参量.然后根据标定出的投影仪镜头畸变参量对理想相位施加反向的畸变,在投影时反向畸变的光栅通过镜头畸变,又成为理想的光栅,从而简化了相位-高度映射关系.实验中,虽然由于测量误差的影响,校正后的投影仪径向畸变系数还是比原来小了1个数量级.     

软模板法制备二氧化钛纳米晶及表征

以钛酸丁酯为原料,正负表面活性剂自组装形成的囊泡为软模板,制备了二氧化钛纳米晶.采用XRD,TEM,TG-DSC,SEM和EDS,XPS等对二氧化钛纳米晶的微观结构进行表征.结果表明:二氧化钛纳米晶在囊泡双层膜内部,双层膜之间和外部均有析出;150℃,450℃,500℃,750℃,830℃焙烧得到锐钛矿相和金红石相二氧化钛纳米晶,并且随温度升高,锐钛矿相二氧化钛含量先增后减,500℃焙烧产物锐钛矿相二氧化钛含量最高,950℃焙烧产物只含有金红石相二氧化钛,二氧化钛纳米粒子呈不规则五边形,尺寸在80～110 nm之间.750℃焙烧产物对活性艳红具有较好的光催化活性.     

La2O3/BaCO3上甲烷氧化偶联反应动力学与历程

以8％La_2O_3/BaCO_3为催化剂,用无梯度反应器,在720～800℃温度范围内,通过改变甲烷与氧分压进行了一系列的甲烷氧化偶联反应动力学测量,确定了该反应的反应历程。乙烷和大部分CO_x(主要是CO_2)是甲烷氧化的一次产物。乙烯是乙烷串行反应的产物。用幂式动力学方程拟合动力学试验数据,估算了各步反应速度方程的动力学参数。还用脉冲反应技术与过渡应答技术证明了参与活化甲烷的是催化剂表面上的可逆吸附氧。     

赤道几内亚巴塔地区产妇分娩时间分析

为分析赤道几内亚巴塔地区产妇分娩时间有无集中趋势 ,准确记录了 3 0 66例单胎足月顺产产妇分娩时间 ,并进行了统计学分析。结果表明 ,y =0 2 3 64 ,x =-0 1 0 7865,r =0 2 598,仭=1 1 4 52°,s=94 0 7,仭 >S ,故P <0 0 0 5。结论 :该地区分娩时间存在集中趋势 ,以当地 7时3 8分为中心 (P <0 0 0 5) ,提示援外医务人员予以重视。     

荧光光谱成像技术结合聚类分析及主成分分析的藻类鉴别研究

为探讨快速、实时藻类检测方法,实验通过荧光光谱成像技术结合模式识别方法对不同藻类进行鉴别研究。发现藻类样本存在着显著的荧光特性,通过采集40个藻类样品的荧光光谱图像,对图像进行去噪、二值化处理,确定有效像素后,根据光谱立方体绘制每个样本的光谱曲线,将所得400～720 nm区段范围内的光谱数据作鉴别分析,再利用系统聚类分析及主成分分析两种不同的模式识别法对光谱数据进行处理。系统聚类分析结果表明： 采用欧氏距离法及平均加权法计算样本间的聚类距离,在距离L=2.452以上水平处可将样本正确分类,准确率为100%;主成分分析结果表明： 通过对原始光谱数据进行一阶微分、二阶微分、多元散射校正、变量标准化等预处理后,再对数据进行主成分分析,其中二阶微分预处理后鉴别效果最佳,八种藻类样品在主成分特征空间中独立分布。因此,利用荧光光谱成像技术结合聚类分析法及主成分分析法对藻类进行鉴别是可行的,操作简便、快速、无损。     

广州市孕妇头发微量元素含量测定

测定了286例不同孕周孕妇头发锌、铁、铜、钙、锰、铅含量,并进行了比较分析。结果表明,孕期上述元素的异常率分别为：40．21％、37．76％、15．04％、45．46％、19．58％、27．97％。不同孕周变化各有差异,以孕中期变化最为明显（除铜和锰外,P＜0．01）。提示妊娠期妇女有益微量元素缺乏的现象是很普遍的,妊娠中晚期事理调整膳食结构和营养物质的补充是必要的。